Sports balls, especially balls for sports like soccer, are usually made by sewing individual pieces of leather or synthetic leather together (sewn balls), or by gluing panels made of plastic onto a bladder (laminated balls).
A sewn ball is made from a plurality of pieces of leather or synthetic leather, and edges of the pieces are folded inwardly and sewn together with a needle. By choosing pieces of leather or synthetic leather with a certain geometry, an approximately spherical shape may be obtained when the pieces are sewn together. For reinforcement, fabric is usually glued to backs of the pieces of leather or synthetic leather. Usually a bladder, for example, a bladder made of rubber, is placed into the sewn ball, which ensures necessary air tightness. The bladder also has a valve for inflating the sports ball.
In both a laminated ball and a sewn ball, a carcass of fabric or a carcass of at least one encircling thread is usually arranged between the bladder and the panels or pieces of leather or synthetic leather to strengthen and protect the bladder. The carcass also enables pressurizing of the bladder during manufacture of the sports ball in order to laminate the sports ball with panels, for example. Without the carcass, the bladder would expand too much and take on a diameter significantly larger than a diameter of a finished sports ball.
How to warp-knit or weft-knit a carcass for sports balls is known. For example, U.S. Pat. No. 8,192,311 B2 concerns a sports ball with a sheath, a textile retaining structure, and a bladder. The sheath forms at least part of the outer surface of the ball. The retaining structure is arranged in the sheath and contains a textile element with a seamless segment having a non-level configuration. The bladder is arranged in the retaining structure. The textile element may be a knitted fabric.
However, a disadvantage with such knitted carcasses is that they are inhomogeneous and not shape-stable. In these knitted carcasses, loop size increases greatly towards the “equator” of the carcass while the loop size is much narrower at the “poles” of the carcass, and thus more material is present at the “poles” of the carcass than at the “equator”. The term “equator,” in this context, is intended to refer to a circular band that divides the carcass into two equal halves. The term “poles,” in this context, is intended to refer to pairs of points on the carcass that lie on a straight line that passes through the center of the carcass and which are positioned equidistant to the equator. The carcass is therefore inhomogeneous, which causes an imbalance in a sports ball in which the carcass is used. Furthermore, the carcass may no longer protect, or may only inadequately protect the bladder against external applications of force “near the equator”, such as when the sports ball is hit or kicked.
It is therefore an object of the present invention to provide a warp-knitted or weft-knitted carcass for a sports ball that is shape-stable and homogeneous, and protects a bladder against external applications of force.